Study on Nonlinear Conductivity Characteristics of SiC-Based Corona-Resistant Tapes

The development of corona-resistant tapes with excellent nonlinear conductivity is essential for improving the reliability of high-voltage variable-frequency motors. This study systematically investigates the nonlinear DC conductivity properties of two domestically produced SiC-based corona-resistant tapes, DECJ2419 and DECJ2420. Using DC conductivity testing, the threshold electric field <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$E_{t}$</tex> and nonlinear conductivity coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex> were analyzed. Both materials exhibit distinct nonlinear behavior.-DECJ2419 demonstrates a lower <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$E_{t}$</tex> and significantly higher <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{\beta}$</tex> compared to DECJ2420, indicating a more pronounced nonlinear response. The conductivity mechanism under high electric fields is attributed to the combined effects of space-charge-limited current (SCLC) and tunneling phenomena. It is inferred that the superior nonlinear performance of DECJ2419 stems from a microstructure with a higher SiC filler content and larger particle size, which enhances the tunneling effect. These findings provide a theoretical basis for the rational design and selection of corona-resistant insulation materials for high-voltage applications.